1. Field of the Invention
The present invention is concerned with road surface marking for traffic regulation, that is with forming, on the upper face of roadways and other areas open to vehicle traffic, traffic regulating signs, such as roadways center-lines, traffic lane dividing lines, roadway edge lines, pedestrian crossing marking strips and so on.
More particularly, this invention is concerned with forming said surface markings or signs by selectively positioning on and fixedly securing to the upper face of roadways (and corresponding roadable areas) prefabricated tape materials which, in service, will form portions of the roadable area, said tape materials being of the kind provided with retroreflective elements partially embedded into or otherwise secured to the upper traffic wear resisting layer thereof, for improving nighttime visibility of the marking.
2. Description of the Prior Art
The art of producing and applying such tape material is a well worked one and wide patent literature thereabout exists. Recently developed and improved tape materials provided with highly efficient retroreflective elements have been described, for example, in the U.S. Pat. No. 3,781,083 (British Pat. No. 1,367,240 and German Patent Application P 22 34 384.6), U.S. Pat. No. 3,935,365 (British Pat. No. 1,463,681 and German Patent Application P 24 03 398.5), U.S. Pat. No. 3,981,557 (British Pat. No. 1,443,618 and German Patent Application P 24 41 491.3) and other, all of the Inventor of the present invention.
Very broadly speaking, the retroreflectivity, that is the nighttime visibility at distance, upon retroreflection of the light emitted by the vehicles headlamps, is grossly proportional to the sharp upwardly jutting out the elements above upper surface of the signalling tape material.
It is evident that the compounding and the manufacture of said roadway surface marking tape materials take into consideration the wear and the severe abuse of vehicle traffic and the stresses which are unavoidably applied by the vehicle passage thereover, in particular during positive and negative accelerations and even during an emergency braking. An extremely destructive action is however exerted by the passage of snowplowing machines and vehicles, in particular of the type provided with snow flangers or blades designed and positioned for exert a somewhat doctoring action for scraping off and displacing away the snow layer from the road pavement surface. Those skilled in the art are well aware that no sharply protruding retroreflective element of the type referred to above can resist to the scraping action of said snow removing means or, conversely, the entire tape material can be stripped or torn off from the road surface by a snow scraper implement impinging on such protruding elements, if exceptionally firmly secured to the tape material.
It is therefore an object of this invention to provide a new and improved roadway surface marking tape material which is substantially not prejudiced or affected by the passage and action of currently used snowplowing machines, and therefore capable of maintaining efficiency and nighttime visibility during wintertime or in any case when the weather requires even repeated snowplowing of the road surface.